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Re: Tesla Coil RF Transmitter

Original poster: dave pierson <davep@xxxxxxxx>

Tesla list wrote:

1 -- the earth is conductive, or we would not be grounding equipment in it 

   'earth' has varying conductivity from place to place.
   Its somehwat lossy, except in really lonarge chunks.
   Its not used in transmitting power.
   (there is a range of conductivity:
      roughly:
      silver
         gold
            copper
               (big gap)
                  'earth' (wide range of values)
                     (big gap)
                        Glass
                           air

The first few are 'conductors', the last few 'insulators'. Materials can be found
in all ranges.

2 -- RF can be conducted thru a conductor, or coax would not exist. 

   Coax uses Really Good Conuctors.
   'earth' isn iffy, and poor, at best, conductor.
   (The values can be looked up in any standard engineering reference, the
   'earth' values will vary widely....)


3 -- given the above statements, why is it so hard for anyone to believe that Tesla was transmitting by conduction through the earth, and not propagation through the air?! Just becuase you CAN transmit RF through the air, doesn't mean it is the ONLY way to do it. 

   Transmission thru earth is lossy.

When tesla was working in Colorado Springs, he worked out two ways of detecting high frequency currents. He had a very sensitive receiver, which seems to have been a precursor to the regenerative radio receiver. 

   He had relatively prmitive thermal detctors,  cf the Colorado SPrings Note.

Then he was also able to receive substantial currents (enough to light light bulbs) using a second Tesla coil tuned to the transmitted frequency. 

   a) When the bulbs, etc, were outside the lab door.
   b) at low efficiency.
   In any case, its straight RF.  Can be duplicated near any broadcast
   transmitter...

Why would he need two different methods of receiving (one really sensitive, and one brute force) if he was not transmitting in two different ways?

Standard radio can be received in lots of different ways. some batter then others,
some better for specific uses.

And Sam, you said the TC transmits poorly; considering that Tesla was lighting up light bulbs with his receivers, seems his coils were transmitting just fine... 

   Suggest reviewing:
      power in
      power out
      distance.

Some of his earlier experiments involved running a loop of cable around his laboratory. He would run RF through it, and light up special bulbs anywhere in his lab. 

   can be done today.  Not real efficient, stray effects of large RF fields
   are unknown.

   best
      dwp